The invention relates to pipe connectors, and in particular, to releasable connectors for which rotation during assembly is difficult, such as piles, risers and conductors used for offshore oil production.
In driving of pilings for offshore platforms, pipe in the order of 30 inches in diameter is used in joints about 50 feet long. As the string is driven, additional joints are added at the top. The connection between joints should effectively transmit the pile driving forces and adequately handle the bending moments and rebound forces.
Risers and conductors, usually in the 20 inch to 30 inch diameter range, and in joints about 50 feet long are sometimes pile driven. They must reliably support tension placed on them when tensioning or running the string during drilling and producing operations. They must also tolerate high bending forces caused, for instance, by ocean currents.
Each of the above situations has in common the difficulty in making up the joints. Wave motion and wind create continuous movement, especially when work is carried out from a work boat. Equipment to facilitate the operation may not be available at this time. Welding is time consuming, and presents a fire hazard. Rotated threaded connectors are difficult to accurately align, and it is often difficult to obtain the high torque required to make up these connectors. With the large diameter and heavy joints, slight misalignment can cause cross-threading or jamming of the threads.
Stab type joints with latching dogs are relatively expensive. Other snap connectors cannot be readily disassembled.